Macroscopic network properties and short-term dynamic simulations in coastal ecological systems at Fildes Bay (King George Island, Antarctica)

A trophic mass-balanced of the benthic/pelagic system dominated by large brown macroalgae in Fildes Bay (Antarctica) was constructed by integrating biomass, production, food spectrum, and consumption related information. The resulting trophic model was used to determine the macroscopic (emergent) properties, overall health and propagation of dynamical higher order effects within this complex Antarctic ecological system in response to simulated impacts. The magnitude of the Relative Ascendency, Relative Overhead, and Redundancy values indicates that the coastal benthic/pelagic Fildes Bay system is likely to remain less developed and therefore more resistant to perturbations than other ecological systems dominated by brown macroalgae. In terms of model component contributions to the Ascendency, detritus accounted for ∼33% of the value, followed by the phyto-zooplankton complex (∼26%), macroalgae (∼19%), filter-feeders (∼7%), small epifauna (5%), and top predators (2%). Short-term or transient Ecosim dynamical responses to increase the total mortality of each model component-given mixed and top-down vulnerabilities-revealed that changes in macroalgae levels had a limited impact on the other components of the system. The filter feeder, small epifauna and benthic fishés functional groups had the greatest effects on the remaining Fildes Bay system components. The magnitude of the System Recovery Time indicated that the Nacella concinna and small epifauna components would take the longest time to return to their initial state. Based on the outcomes obtained from the model, we suggest that this preliminary trophic model, including simulated impacts, provides promising possibilities for the determination of macroscopic baseline conditions and the most sensitive components of the Fildes Bay ecological system.